Two Russian fighter jets and two military transport helicopters crashed in southern Russia on Saturday, while Ukrainian forces struck deep into Russian-controlled territory in eastern Ukraine, moves that suggest Kyiv’s military capabilities are growing.

The crashes are the worst losses for Russia’s military aviation since the first week of its full-scale invasion of Ukraine in February 2022, when Moscow mistakenly assumed that Ukrainian air defenses had been destroyed. It has lost more than 70 planes since then.

Russian state news agency TASS said a Su-34 fighter and a Mi-8 helicopter went down Saturday in Russia’s Bryansk region. Another Mi-8 and a Su-35 also crashed, according to Russian military correspondents and an official of a Russian proxy state that claims territory in eastern Ukraine.

Meanwhile, Russia claimed that Ukraine used U.K.-supplied cruise missiles in strikes on Luhansk, an area controlled by Russian forces in eastern Ukraine.